A low molecular weight factor from sea urchin eggs that elevates sperm respiration rates as well as sperm cyclic GMP concentrations will be purified in quantities sufficient for chemical and biological analysis. Large preparations of the factor will be purified by a combination of charcoal adsorption and DEAE-Sephadex chromatography, gel filtration, and high pressure liquid chromatography. Other purification methods such as preparative electrophoresis will be attempted if necessary. Initially, the chemical composition of the factor will be analyzed on a qualitative basis after paper and thin-layer chromatography. Various spray reagents will be used for the qualitative analysis. Based on these results, quantitative analysis of the factor will be pursued. Attempts will be made to label the purified factor with 125I or 3H, and preliminary experiments will be initiated to determine whether or not the labeled factor binds to a sperm receptor. Attempts also will be made to produce antibody to the factor after coupling it to thyroglobulin or some other large protein. The effects of the purified factor on sperm respiration rates, oxidative metabolism of fatty acids, and cyclic GMP and cyclic AMP concentrations will be studied in depth. Emphasis will be placed on the mechanism of action of the factor and of 8-Br-cyclic GMP to stimulate the oxidation of sperm lipids. Agents that are known to increase cyclic GMP concentrations in various tissues will be tested for effects on sperm cyclic GMP concentrations, rates of respiration, and rates of oxidation of added fatty acids. The factor also will be tested for effects of sperm guanylate cyclase and phosphodiesterase as well as for effects on the sperm obtained from animals other than the sea urchin.